1. Field of the Invention
The present invention relates to a hydraulic signal output device that outputs a hydraulic signal in accordance with a manual operation to an external actuator.
2. Description of the Related Art
An operation room of a hydraulic shovel is provided with a pilot pressure oil output device that outputs pilot pressure oil in accordance with an operation of such as an operation lever. When an operator tilts the operation lever fore and aft, from side to side, and obliquely, a movement of a vehicle can be controlled.
FIG. 20 shows an operator's seat 100 disposed in an operation room. Sideward to the operator's seat 100, a lever stand 80 is disposed. The lever stand 80 is provided with a hydraulic signal output device constituted of a PPC valve. An operation lever 7 is attached to the hydraulic signal output device and disposed so as to project upward from the lever stand 80. FIGS. 21A through 21C are a side view, a plan view and a bottom view, respectively, of a hydraulic signal output device 50 to which the operation lever 7 is attached, and as shown in these drawings the hydraulic signal output device 50 is accommodated in the lever stand 80.
FIG. 12 is a sectional view of a hydraulic signal output device having an operation lever. In the hydraulic signal output device 50, when a single operation lever is tilted, each of four pistons outputs outside a hydraulic signal in accordance with its displacement, specifically pilot pressure oil is outputted. When the operation lever is tilted, the pilot pressure oil is outputted, the outputted pilot pressure oil is guided to a not shown operation valve, and thereby an operation valve is operated. When the operation valve is controlled, a hydraulic motor that makes a vehicle run or a hydraulic cylinder that operates an operating machine is controlled in their movement. The hydraulic signal output device 50 is called a PPC valve.
Furthermore, in some cases, a hydraulic signal output device that outputs pilot pressure oil in accordance with an electrical signal is disposed. When an operation is carried out in, for instance, a dangerous spot, it is dangerous for an operator to ride and operates a vehicle. In such a case, an operator operates a remote control device externally of the operation room and sends a radio signal to the hydraulic signal output device. Based on the received signal, a current flows in the hydraulic signal output device, and the pilot pressure oil in accordance with a magnitude of the signal is outputted.
FIG. 13 is a sectional view of a hydraulic signal output device that outputs pilot pressure oil in accordance with an electrical signal. A hydraulic signal output device 60 outputs pilot pressure oil in accordance with a thrust force of a plunger 26. The hydraulic signal output device 60 is disposed corresponding to each of pistons of the hydraulic signal output device 50. Accordingly, when the hydraulic signal output device 60 is remote-controlled, a movement of a hydraulic motor that makes a vehicle run is controlled. The hydraulic signal output device 60 is called a proportional EPC valve, and a thrust force that is proportional to a magnitude of a current that flows in a solenoid coil 25 acts in an arrow mark U direction.
As shown in FIG. 14, in the case of the PPC valve 50 and the EPC valve 60 being provided to an operation room of a vehicle, a shuttle valve 30 that connects the PPC valve 50 and the EPC valve 60 is disposed.
The shuttle valve 30 outputs the pilot pressure oil of a higher-pressure one of the PPC valve 50 and the EPC valve 60. The pilot pressure oil is input into an operation valve that controls pressure oil that is supplied to the hydraulic motor. Accordingly, when the operator operates the operation lever or the remote-control device, a vehicle is made run or the operating machine is made to operate.
However, when the PPC valve 50, the EPC valve 60 and the shuttle valve 30 are disposed separately in the operation room, there is necessity of connecting between these PPC valve 50, EPC valve 60 and shuttle valve 30 through a pipe line such as a hose and so on, resulting in a large installation space. Accordingly, there is a problem in that a space other than the hydraulic machines in the operation room becomes relatively smaller.
The present invention is carried out in view of such situations and a first object of the present invention is to provide a hydraulic signal output device having a smaller installation space, and thereby making the installation space of the hydraulic machines in the operation room relatively smaller and thereby making a space other than the hydraulic machines relatively larger.
In some cases, however, the operator may manually operate wrongly and allow the vehicle to intrude into a dangerous spot. In this case, the operator is mostly not aware of the vehicle having intruded into the dangerous spot. At the time of such wrong operation being performed, unless some measures are not applied from the outside, the vehicle is allowed to intrude into a further dangerous spot.
Furthermore, in some cases, an operator unfamiliar to the operation of the PPC valve 50 may not move the vehicle as he wants.
The present invention is carried out in view of these situations, and a second object of the present invention is to allow externally limiting the operation in the operation room.
Actually, a shape of the lever stand 80 shown in FIG. 20 can be various because of the restrictions resulting from a layout of the operation room. Accordingly, depending on the shape of the lever stand 80, different from one that is shown in FIG. 21, the hydraulic signal output device 50 may not be accommodated inside of the lever stand 80.
The present invention is carried out in view of such situations and a third object of the present invention is to allow the lever stand 80, irrespective of the shape thereof, to accommodate the hydraulic signal output device therein.